Nitric acid dihydrate at ambient and high pressure: An experimental and computational study

Abstract

The high pressure structural behavior of nitric acid dihydrate $({[{\mathrm{H}}_{3}\mathrm{O}]}^{+}∙{[\mathrm{N}{\mathrm{O}}_{3}]}^{\ensuremath{-}}∙{\mathrm{H}}_{2}\mathrm{O})$ has been investigated up to $3.8\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ using single crystal x-ray diffraction and neutron powder diffraction techniques. A new structural phase has been identified above $1.33\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ and this has been further studied by ab initio quantum mechanical calculations. These have guided the refinement by neutron powder diffraction.